This invention relates to a trencher having a roller chain carried on a chain bar. More particularly, this invention relates to the structure of the chain bar and to a safety guide that is adjustable in concert with the chain bar.
Trenchers are known having an elongated chain bar that extends outwardly from the trencher frame in a cantilever manner. Such trenchers include a roller chain that is configured to cut, dig or otherwise remove material such as dirt or soil to create an elongated trench in the ground. The roller chain loops around the chain bar. The trencher frame carries a motor for powering the roller chain so that digging or cutting teeth provided on the roller chain will cut or dig soil as the roller chain is driven around and around the chain bar.
In prior art trenchers, the chain bar is typically formed of two major pieces that are secured together. The first piece comprises a stub fixed to the trencher frame. The second piece is an elongated boom having a socket at one end telescopically inserted over the stub. The boom is clamped to the stub by various bolts which pass through the boom and over the top and bottom surfaces of the stub.
Because the bolts used to clamp the boom to the stub press against the top and bottom surfaces of the stub, the height of the stub is quite small to accommodate the thickness of the bolts. Thus, for a given sized boom and drive sprocket carried on the boom, the attachment between the stub and the boom is not as robust or durable as might be desired due to the small size of the stub. Thus, a better way of attaching the boom to the stub is desirable in the art.
In addition, prior art trenchers have typically been built such that the chain bar is located in a first or normal position on one side of the frame. A safety guide or bar has been provided above this first position of the chain bar. In some prior art trenchers, the chain bar can be moved to a second or offset position on the other side of the frame. However, the safety guide does not move with the chain bar as it is typically installed only above the first position of the chain bar and cannot be installed in any other position. Thus, when the chain bar is moved to its second or offset position, it is used in this position without the safety guide being located above it, which is disadvantageous.
One aspect of this invention relates to a trencher for digging trenches. The trencher comprises a trencher frame. A chain bar is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. An endless chain having digging teeth is provided with the endless chain being carried on the chain bar. The chain bar comprises a base member secured to the trencher frame which base member carries a stub having a longitudinal axis, an elongated boom having a socket at one end which socket is slipped over the stub of the base member, a slot in the stub with the slot extending parallel to the longitudinal axis of the stub, and at least one bolt passing through the boom and the slot to secure the boom to the stub.
Another aspect of this invention relates to a trencher for digging trenches. The trencher comprises a trencher frame. A chain bar is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. An endless chain having digging teeth is provided with the endless chain being carried on the chain bar. A safety guide is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. Both the chain bar and the safety guide are adjustable on the trencher frame between two laterally spaced positions with the safety guide overlying the chain bar in both of the two laterally spaced positions.